Nitroglycerin transport



N 1954 ALEXANDER v. d. LUFT EI'AL 2,694,404

NITROGLYCERIN TRANSPORT Filed Sept. 24, 1952 IN VENTORS ALEXANDER v. d.LUFT VINCENT H. WALDIN SAMUEL E. WALKER PHILIP G. WRIGHTSMAN ATTORNEYS2,694,404 "NTTROGLYCERIN TRANSPORT Alexander v. d. Luft," Clarksboro,N.J. ,"'Vinc'ent"H. Waldin, N ewpo'rt, and Samuel E; Walker, Wilmington,Del., andiPhilip G; Wrightsman, Swarthmore,Pa.,"as- ""signors tdE. IsduPont de Nemours & Company,

Wilmington, Del., a corporation of'Delaw'are Application-September 24,1952, Serial No. 311,246 3 Claims. (Cl. 137-1) -The :presentinventionrelates to a-novel method and States Pateti't' O apparatus.fortransporting liquid'explosive nitric esters safely andefliciently.

Nitro'glycerin: is a highly sensitive liquid explosive-used in -themanufacture of commercial dynamite, and is prepared by the nitration'ofglycerin. In the pure-liquid state, the sensitivity of the nitroglycerinis so great that evenminute disturbances may cause a detonation. Forthis-reason, it has long been the practice in the-explosivemanufacturing industry to remove the nitroglycerin from the nitratorassembly as it is produced, and to store it in small quantities atwidely scattered storage areas until thedyna'mite-mixing house is readyto use it immediately,-and-then to deliver the liquidnitroglycerin insmall lots as it is used.

- The -dynamite-mixing houses are located a considerable distance fromthe nitrating apparatus to localizeany accidental detonation which mayoccur.

iWhile various methods for transporting nitroglycerin have beenproposed, the most widely acceptedmeans has continued to be hand-pushedtank-carts having rubbertired Wheels and made of non-sparking materials.JBy design, these carts are capable of carrying only a very smallquantity of the liquid explosive, and the runways provided for the cartsmust be maintained free of any obstruction and remote from any Workareas. Thus, this procedureis both costly and inelficient, and, inaddition, requires repeated handling of the highly dangerous andunpredictable nitroglycerin.

Nitroglycerin, as the termis generally used in the industry, isnot'restricted to'glycerol trinitrate, but includes also other explosiveliquid nitric esters such as nitrated ethylene glycol, or variousnitrated sugars such as glucose andsucrose. Frequently, a mixture ofliquid explosive nitric :esters is prepared .by nitrating the rawmaterials together. Therefore, throughout this description, the termsnitroglycerin and liquid explosive nitric ester are interchangeable, andboth terms include mixtures of liquid explosive nitric esters.

It is an object of the present invention to provide a safe and eificientmethod for transporting liquid explosive nitric esters without the useof manual means. A further object of the present invention is to provideapparatus adapted to accomplish the foregoing method of transportingliquid explosive nitric esters. Additional objects will become apparentas this invention is more fully described.

We have found that a liquid explosive nitric ester can be safelytransported in pipes When it is first intimately mixed with water toform an emulsion, and the emulsion thus formed is transmitted throughthe pipe in relatively short columns separated by columns of water. Awater emulsion of nitroglycerin is substantially incapable of beingdetonated, and by providing columns of water between columns ofnitroglycerin in a pipe, absolute certainty is obtained that even if onecolumn were detonated, for example, due to separation of the emulsion,the detonation would not be transmitted along the entire length of pipe.

To accomplish the foregoing method of transporting liquid explosivenitric esters, we use an eductor, wherein water under pressure creates asuction which draws either the ester or water into a mixing chamberwithin the eductor, and feeds the emulsion thus formed, or the watermixture into the transport pipe.

In order to more fully describe the present invention,

reference is 1 made i "to thei accornpanying 'tdrawing, Lin which:

Figure 1 is azrschematic. diagram 'of at nitroglycerin transportassembly in accordanceirwith thezapresentf invention;;and.

Figure; 2 is a" sectional-view carryout thepresentmethod. .1 In Figure1,- 1lrepresents.a nit-ratoreasse'mbly, includingneutralizers and the'preliminarywash apparatus,- 2 is a nitroglycerin reservoir, and-3is-aswatenresetVoir. 4 representstheeducton fully detailed in Figure 2.an5zis a water-pumpt-assernbly, includingcontrol :valves; etc., toregulaterthe"pressure.andhmaintain ar'constant flow. 11-6 represents twoair-operated valves, 7 represents axsource of air pressure, 8 representsa.solenoid operated valve adapted to regulate 'the" fiow' of air underpressure into or out of the air line to valves ,6, and 9' is a.timer-.controller adapted to regulate the operation of "solenoidoperated valve8. 10 representsthe 'nitroglycerinItransport "pipe, 11 is' awater-returnpipe, 12 is the. suction of van 'eductonadapted to tube, and 13represents the water inlet tube from pump 5" to 1 eductor 4. Pl4rirepresents anernulsion-brealcing separator assembly,..and. 15represents a 'pipe from the separator 14 to the point .of utilization.ofm-the l-nitroglycerin.

In Figure 2, 4 :representsuthe. body ofnthe eductor wherein16.is.an1'inlet.- tube havinga nozzle-17. =.The nozzle 17 PIOjGCtSi'into-the chamber 18 formed Iati'the junction of: suction tube 12'withthebody .4. The'throat 20 in body 4-lies between theconvergent'sexit.t2lxfrom chamber :18 and thedivergent.exit:22Ileading.to.thertransport pipe 10.

:The operation :of the present .system is as follows: Water.underpressure. fromxpump 5 passesthrough -pipe 13 to the eductor-4,enteringthrough inlet tube 16xand nozzle. Due -to'thereduced opening.provided by. the

nozzle, the Water velocity. past the nozzle is considerably greater thanthe velocity in .pipe .13... The: highl-velocity stream of waterissuingfrom .nozzle 17 produces a reduced pressure area laroundathelnozzlein.chambent.:-18,

- thus 'drawing liquid through the suction .tube. 12, the

liquid thus drawn: depending :.upon. the positions. of valves 6.

Due to theturbulence in chamber 18, the liquid. drawn throughitubel 12is intimately intermingled with: the water stream from nozzle 17; Wherenitroglycerin is theliquid,

theintermingling produces. an aqueous emulsion; :lThe intermingledliquids enter the :transportpipe 10 via. the convergent. exit 21, thethroat 20 and thedivergentexit 22,:additional turbulencebeingpresentthroughout, and

breaking separator '14, where the separated nitroglycerin, having ahigher specific gravity than water, is removed from the bottom throughpipe 15, and the separated water is returned to pump 5 through pipe 11.

The level of nitroglycerin in reservoir 2 is maintained by flow from thenitrator 1, and the water level in reservoir 3 is maintained by eitherproviding a return from pump 5 or by a fresh water source, neither beingshown. Preferably, provision is made for purging the water system andintroducing fresh water to pump 5.

Valves 6 are so adjusted that in the absence of air pressure, the valvein the nitroglycerin line is closed and the valve in the water line isopen. When air pressure is applied, the valve in the water line closesand the valve in the nitroglycerin line opens, thereby providing for afail-safe condition. Timer controller 9 can be adjusted to energize andde-energize the solenoid valve 8 at any desired frequency. Valve 8, in adeenergized position, vents the line to the valves 6, and in theenergized position connects the line to the air-pressure source 7,thereby also creating a fail-safe condition. By the term fail-safecondition, We mean that in the event any of the mechanism fails tooperate, the liquid being transported will be water, and there will beno accumulation of nitroglycerin at the receiving end, or a solid columnof emulsion in the transport pipe 10.

The following example is presented only for the purpose of illustratingthe present invention, and does not constitute the limitation thereof.

Using an arrangement substantially as illustrated in Figure 1, whereinthe pipes '10, 11, 12 and 13 all had an inside diameter of 0.569 inch,the distance from the nitrator assembly 1 to the separator 14 wasapproximately 600 feet, and the suction lift was about 3 feet, theassembly had the capacity to deliver 700 pounds of nitroglycerin perhour using a water pressure from the pump of 30 pounds per square inch(gauge).

In the above assembly, the nozzle tapered at an angle of 7 to an insidediameter of 0.1575 inch, the convergent exit tapered at an angle of 15to the throat, the distance of the throat from the nozzle being 0.72inch. The throat had a diameter of 0.3 inch and a length of 0.4 inch.The divergent exit had a taper of 3.35%. Using these dimensions, theaqueous emulsion formed contained 43% nitroglycerin by weight.

The amount of nitroglycerin which can be delivered per hour using thepresent assembly .depends upon the following factors:

(a) Diameter and length of the transport pipe (b) Water pressure Eductordesign and ratios (d) Suction lift distance (e) Length of emulsioncolumn with respect to length of water column.

When a system has once been established, only factors (b) and (e) arereadily variable, and therefore constitute the operational control ofthe present method. For maximum safety, we prefer to limit the length ofthe nitroglycerin column to not more than 75 feet, and the length of thewater column to not less than 20 feet. The pressure at the eductorshould be such that a transport line velocity of at least 3 feet persecond can be maintained, the upper limitation on velocity being thecapacity of the emulsion breaker-separator assembly. The length of thesuction tube should preferably not exceed 8 feet for satisfactoryoperation. in order to reduce the danger of detonation the emulsion inthe pipe should have a composition of not less than 30% water.

Preliminary separation of the emulsion may be obtained by simplyenlarging the diameter of the pipe at the exit end of the transport linesufficiently to reduce the velocity of the mixture, thus reducing theturbulence. With a low line velocity, the emulsion is readily broken,and about fifteen feet of enlarged diameter pipe would be suflicient tofacilitate rapid separation at the subsequent apparatus withoutrequiring increased size thereof. Preferably, the transport pipe is madeof material which is essentially not wetted by a liquid nitric ester,for example, polythene.

There are a number of critical ratios in the eductor design which mustbe met for efiicient operation. The nozzle must project past the centerline of the chamber, and the taper angle lie between and 10 degrees. Thedistance from the tip of the nozzle to the throat is between 4 and 5times the diameter 01' the nozzle, and the convergent exit angle isbetween 10 and 20 degrees. The ratio of the diameters of the nozzle andthe throat determine, to a large extent, the composition of theemulsion, that is, the ratio of the water from the nozzle to the totalliquid in the transport pipe is substantially the same as the ratio ofthe nozzle diameter to the throat diameter. Therefore, to maintain anemulsion containing at least 30% water; the ratio of the throat diameterto the nozzle diameter must be at least 1.2 to 1. The length of thethroat lies in the range of from 1 to 1.5 times the diameter of thethroat, and the divergent exit angle lies between 3 and 5 degrees.

The present invention can obviously be adapted to a fully automaticarrangement for the manufacture of dynamite. In such an arrangement, thetimer-controller of the solenoid-actuated valve would be responsive to acontrol at the separator, thereby maintaining a constant level in theseparator by regulating the respective column lengths of thenitroglycerin emulsion and the water. The nitrator assembly would becontrolled so as to provide a predetermined level in the nitroglycerinreservoir. By thus integrating the operation, the storage of appreciablequantities of nitroglycerin would be completely avoided, and continuousoperation assured.

It will be understood that many variations and modifications can be madewithout departing from the scope of the present invention. Therefore, weintend to be limited only by the following claims.

We claim:

1. A method for transporting liquid explosive nitric esters whichcomprises intimately intermingling said liquid explosive nitric esterwith Water to form an emulsion, introducing said emulsion into atransport pipe to form a column within the pipe introducing water intosaid pipe to form an adjacent column within the said pipe, and socontinuing to alternately introduce emulsion and water into said pipe ata pressure sufiicient to provide a flow of at least 3 feet per secondthrough said pipe.

2. A method as claimed in claim 1, wherein the length of the emulsioncolumn does not exceed feet, and the length of the Water column is notless than 20 feet.

3. A method as claimed in claim 1, wherein the emulsion has acomposition of at least 30% water.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,835,603 Kincaid, Jr. Dec. 8, 1931 2,109,611 Axelrad Mar. 1,1938 2,283,907 Berman May 26, 1942 2,379,240 Lobdell June 26, 1945

1. A METHOD FOR TRANSPORTING LIQUID EXPLOSIVE NITRIC ESTERS WHICHCOMPRISES INTIMATELY INTERMINGLING SAID LIQUID EXPLOSIVE NITRIC ESTERWITH WATER TO FORM AN EMULSION, INTRODUCING SAID EMULSION INTO ATRANSPORT PIPE TO FORM A COLUMN WITHIN THE PIPE INTRODUCING WATER INTOSAID PIPE TO FORM AN ADJACENT COLUMN WITHIN THE SAID PIPE, AND SOCONTINUING TO ALTERNATELY INTRODUCE EMULSION AND WATER INTO SAID PIPE ATA PRESSURE SUFFICIENT TO PROVIDE A FLOW OF AT LEAST 3 FEET PER SECONDTHROUGH SAID PIPE.